Immunolocalization of basic fibroblast growth factor (bFGF) in growing and growth-inhibited placental cells: a possible role for bFGF in placental cell development.

The distribution of basic (b) fibroblast growth factor (FGF) in growing and growth-arrested human placental tumour cells, as well as normal placental villous trophoblasts, was studied by immunofluorescence microscopy with antibodies to the amino terminus of bFGF. Placenta (FAR, FEG-3), breast (MCF-7, T-47D), cervix (HeLa) and uterine (HEC-1-A) tumour cells showed the same two patterns after immunofluorescent staining with antibodies to bFGF: (i) a perinuclear pattern and (ii) an intense homogeneous staining of the nucleus and cytoplasm. The homogeneous bFGF staining pattern was associated predominantly with actively dividing cells, observed at different stages of mitosis and cytokinesis. Placental (FEG-3) cell division was inhibited with methotrexate (MTX), a chemotherapeutic agent used in the treatment of placental tumours. MTX-treated FEG-3 cells as well as 'normal' non-proliferative placental (syncytiotrophoblast) cells from term placentae, showed perinuclear staining with antibodies to bFGF and immunofluorescence microscopy. The nuclear localization of bFGF in dividing but not non-dividing placental cells, suggests a role for bFGF in cytotrophoblast proliferation in vivo.